Pleading poverty will not work; at best the organizers will lower the minimum required amount to be spent to something they consider reasonable.

The only way out of it I know of is to claim that you belong to a religioussect that strictly forbids such activities, such as the Jehovah's Witnesses. The problem with this approach is that in order to keep up the pretense you will have to give up everything else the sect you've chosen forbids, which will most likely include things like drinking, dancing, gambling, movies, attending Fourth of July celebrations, and your birthday. Your co-workers will also think you are a creepyreligious nut, and the number of invitations you receive for other, more desirable events will drop off dramatically.